Unless you run synthetic, 3000 miles is a fairly long period. I would not characterize 3000 miles as having "just" changed the oil.
<Editorial mode off>Manufacturers typically say that using (through both burning and leaking) one quart in 1000 miles is "normal," alhtough most engines in decent condition use a lot less than that. My '88 XJ doesn't use a full quart in 5000 miles (synthetic). So ... where can your oil be going?
(1) The rear main seal may be leaking. Look underneath the vehicle, from the bell housing to the rear. Is the underside of the chassis coated with oil?
(2) The valve cover gasket may be leaking. Look for signs of oil dripping down on the ends and sides of the engine.
(3) The oil filter on the 4.0L does not attach directly to the engine. There's an adapter, which is bolted to the block and which has O-rings to seal it to the block. The O-rings get old and begin to leak. Check for signs of leaks around the oil filter adapter housing.
(4) The 4.0L engine does not use a PCV valve. It uses a very small tube at the rear of the valve cover to suck fumes out of the crankcase. It's called a CCV system if you want to run a search. This tube often gets plugged up. When that happens, if there's any blowby at the piston rings the crankcase becomes pressurized and pushes oil back through the larger of the CCV tubes, the one at the front of the valve cover that connects to the air cleaner box. Open the box -- if the air filter element is soaked with oil, you'll know that you have this problem.
(5) Last, of course, is that you may also be burning some oil. Have a friend follow you for several miles. Once the engine is warmed up, do some fairly hard acceleration runs, and also get up to speed and then let off the throttle to coast down on engine braking. Have your wingman watch the tailpipe for blue smoke.
